One of the principal recommendations in The Asilomar Conference Report on Recombinant DNA was that the guidelines for containment
and administrative procedures for recombinant DNA techniques be reviewed continuously. We expected that in time and with
graving experience our views about the nature of the risks would change and this would be translated into corresponding changes
in the detailed recommendations in the NIH Guidelines. It is to your credit that you prevailed in incorporating a procedure
for orderly changes and this procedure, though time consuming, is working.

I do want to take this opportunity to comment on the proposed exemption for E. coli K-12 Host-Vector System from the Guidelines.
When the group of which I was a member expressed our concern about potential risks associated with recombinant DNA research,
we had in mind the possibility that such experimentation might employ a wide variety of E. coli strains and transmissible
vectors as host-vector systems. We imagined that some of these would be able to establish themselves in nature or in the intestinal
tracts of man and animals. Had we known then that E. coli strain K-12 and non-transmissible plasmids or phages would be widely
adopted as the preferred host-vector systems, and that this system would be as secure as all the risk-assessment experiments
have shown, I doubt that we would have raised the issue in the manner we did. I am persuaded by the evidence I have seen that
molecular cloning of any DNA segments in E. coli K-12 using the array of present day cloning vectors is no longer of any real
concern, certainly not enough to warrant the continued inclusion of such experiments within the purview of The Guidelines
and the IBC's. Perhaps it would still be useful to maintain a log of recombinant DNA experiments in this category so
that these experiments can contribute to the ongoing assessment of the safety of such research activities.